Electrical motor controls including non-linear series resonant circuits

ABSTRACT

Electrical controls which include a resonance circuit connected electrically to an oscillator and having a plurality of circuit elements to one of which an output means is connected in parallel. A regulating means coacts with one of the circuit elements for influencing at least one of the parameters of the circuit. For example, the circuit may include an inductance coil and the regulating means may take the form of a permanent magnet which is moved in a predetermined manner with respect to the inductance coil so as to achieve in this way the controls of the invention. The output means is connected through a transistor, for example, to an element such as a stationary coil section of a commutator-less direct current motor, or the structure may act as a switch for controlling a circuit, so that in this way the structure will form an incorporeal switch.

United States Patent [72] Inventor Ernst Lueder Stuttgart Bur, Germany[21] Appl. No. 615,517 [22] Filed Feb. 13, 1967 [45] Patented July 20,1971 [73] Assignee Finn: Gebr. Buhler Nachtolger G.m'.b.1l.Kornerstresse, Nurnberg, Germany [32] Priority Feb. 15,1966 [33] Germany1 L52862 [54] ELECTRICAL MOTOR CONTROLS INCLUDING NON-LINEAR SERIESRESONANT CIRCUITS 1 Claim, 9 Drawing Figs. [52] US. Cl 318/254, 331/65,313/439 [51] lnt.Cl ..1102k 29/00 [50] .Field Search 331/65,77; 340/75;318/130, 133, 138, 259, 59, 439 [56] References Cited UNITED STATESPATENTS 2,980,839 4/ 1961 l-laeussermann 318/254 X 3,214,663 10/1965Kreutzer..... 318/138 3,239,739 3/1966 Scholl 318/138 3,373,327 3/1968Teuber.. 318/138 I 25 i V I r'-""| 1""1 +21 t.-.

4/1968 Neville et a1 318/138 2 ,040,763 5/1936 Summers... 318/133 X2,048,723 7/ 1936 Appleton. 331/77 X 2,146,769 2/1939 Schrieveret al..331/75 2,150,440 3/1939 Hargreaves 331/75 2,205,424 6/1940 Leonard331/75 X 2,325,927 8/1943 Wilbur 331/65 X 2,992,397 7/1961 Roberts331/75 X Primary Examiner-G. R. Simmons Attorney-Arthur O. KleinABSTRACT: Electrical controls which include a resonance circuitconnected electrically to an oscillator and having a plurality ofcircuit elements to one of which an output means is connected inparallel. A regulating means coacts with one of the circuit elements forinfluencing at least one of the parameters of the circuit. For example,the circuit may include an inductance coil and the regulating means maytake the form of a permanent magnet which is moved in a predeterminedPATENTED JULZO l9?! SHEET 2 [IF 2 FIG. 8

25 27" [1 FIG. 9 33 45 44 g I I 43 T I NVENTOR.

ERNST LUDER "mam ATTORNEY E Ec'rnicAiL I .control output is I'connectedin ments of the resonancecircuit.

. it III 31..

i i uni-31 n scams aesonaurcmcurrs The invention relates to electricalcontrols for-'Ivarious purexample, for the purpose of controlling it.

p es Su h 's-f commutatorlessdirectcurrent motor. I I I I Theinventionis characterizedby an electrical resonance circuit which is connec tedto an oscillator andwhich has a regulating means, "in the forntpt atleast one control element,

Marin; c'onrkotstuciiumuc NON [A preferred. rim or the which influencesat'least'one parameter'of the circuit. The

Th 6 der 'to'control cornrnutatorless' direct current motors,

' the re are alre yr b control elements in the form ot movablepermanentwin'agnets which change the ohmic resistance of so-called fieldplates depending upon the magnetic v field. -;In this 'waythe-change inresistance which is brought aboutby the-control e'lementsproduces achange-in potential which; mayI:be .,esed; for example; to actuate a"transistor. .Moreover, cornmutatorless directcurrent motorsare providedwith control elements in the form of movable coils which, ac-

I cording to the angular position of the rotor, are situated within I orwithouta magnetic stray field and thus will have or. will not have aninduced potential at'Jtheir terminals. This inducedv potential isusedcontrol the current in a winding of the motor. It'has also become knownthat a'tran'sforrne'r, which has parallel with oncof the eleparameterswhich can controlled with the invention are also elements such as anohmic resistance connectedin series with the inductance andcapacitance-and whose resistance can, for example, depend uponthemagnetic inductionfthc applied potential, thejcurrent, or. the amount oflight which is received. It is also possible to bring about reversals bymeans of control elements which'are ltnown in themselvesian'd whichare'capable of influencing the output potential and/or the frequency ofthe :oscillator. Beside controlling a commutatorless direct currentmotor, the electrical controls of. the invention can'also be used-withsuch structures as an electronic ignition installation forautomobiles;for the control of washing machines',-. for. the control of bookkeepingor accounting machines, aswell asother machines where controlledcontacts .been strongly premagne tized by amagnetic field-will, becauseof its saturation, be incapable of 'producingany secondary, potential].This secondary potential increases, however, when the premagne'tizirigi'seliminatedl Thus, this secondary poten- I tial which is dependentuponthe prema gnetizing lendsitself to eontroltfw 1 {Ihe'range ot'uses'ofknown structures of the above type is limitedon the one hand. becausethe extent to whichchanges in' potentialca'n achieved is relativelysmall and onthe other-hand; because'the control potential .alwaysincreases gradually, and not -in-a;sudden jump, from a small amplitude I.intoalargeamplitude. 1

It is a primary object of the present invention. to provide .electrical-controls, which will go beyond the; limits of the linown'con'trol'sand-which will=provide many" more uses for the controls- Thus} it is anobjectaof the-invention provide controls which are not only capable ofachieving a change in" value of an electrical control element but-alsocontrols which are'capa- I bleot influencingan entireresonancecircuitq'Thus, ir san object of the invention as provide by a, or thecorit'rolsofiit-he'invention much greater potential changes thancould heretoforebe achievedat the. outputs of the known FIGS 2 and 3 respectivelyillustrate characteristic curves of are required; Thus','the inventionis capable of being used at any location where an incorporeal contactarrangement is required.

The invention is illustrated by way of example in theaccompanyingrawings which form part of this application and in which j Y.3 11 FIG. I illustratesa nonlinear oscillatory series circuit;

a lt llinear oscillatory" series circuit;

. FIG}! is a fragmentary schematicrepresentation showing in anaxial'sectional view thecons'truction of a commutatorless direct currentmotoraccordingtotheinvention;

FIG. 5 is a transversesection ofthe -structure of FIG. 4 takenalong'line'V-V of FIG. 4 in the direction of the direction ofthearrowsi-I FIG. 6 is a-transverse section the structure of FIG. 4

taken along line Vl-VI of FIG. (in the direction of the arrow; FIG. 7is'a wiring diagram of the controls for a commutatorj less directcurrent motor of the invention;

FIG; 1; shows a part of another embodiment Ofa wiring dia- I gram for acommut'atorless direct current motor corresponding in general to thatofFIG. hand structures. With the invention it is possible to achieve theadvantage of'providing for the controlled element's relatively largepotential tolerances with respect to. their throughput gmigl,-theirreversing potential, or other increasing values.

Itis furthermore an object of the invention to provide a constructiorl,which is capable of producing, in a manner described below in greaterdetail, a sudden, sharp, aln tost instantaneous change in the eontrolpotential from a condition 1 [of srnallamplitude into-a condition of,large amplitude, so that I the; controls operate to produce resultssimilar to those I achieved by the suddenopening'and closing of acorporeal switch, the structure ofthe invention thus providing an incor'I poreal switch which although there are no actual contacts engaging anddiseng'aging'eaeh-othenhevertheless will produce similar results.

Therange-of uses whiclt may be made for the structure. of

I the invention is very broad, since it pennits many different types. ofcontrol elements to be used and. can bring about a I reversing action bya change in the inductance, the

capacitance, or the-ohmic resistance, as well'asinthe .am-

I FlG..9 is a fragmentaryillustration of yet an othepembodiment of a"wiring diagram for a commutator-less directcurrent motor correspondingin general to that ofFIG. 7.

- FIGS; 2 and 3 show characteristic curves for an oscillatory seriescircuit having the construction shown in FIG. 1. This circuit includes arelatively sma II ohmic resistor R, an inductance L and a capacitance C,and at least one parameter of this circuit is capable of beinginfluenced by a regulating means of the invention. In the illustratedexample the condition of the circuit is capable changed by manent magnetM on the inductance L. a I

In thecurrent/voltage diagram of FIG. 2, the curve 1 for'the potentialU,,(l) applied at the nonlinear impedance L is illustrated. Also'alinear curve 2 is provided, this curve illustrating the potential [U,+(NW6) 1 depending upon-the'current. The

pl it ude of the. input potential of an os'cillator, or the inventione'anbe'used to ,regulate'the frequency of such anoscillator. In I thisway it is possible to'hav'e linear or nonlinear, parallel orseriescscillatory-circuits.

potential equation forthe oscillatory series circuit, in the 7 eventthat the circuit is inductive and the ohmic resistance R is IIneglected,isv I .i I u.=t 1, n'- t/ so'thet II I tu)="v. +m/wc) v Thepoints 'S, at'which two voltage curvesintensecteach'othenare possibleoperating points of the oscillatory circuit where the intersectionpoints3.and4 illustrate stable the influence ofa perl operating points and theintersection point 5 indicates an unstable operating point, as isknownfrom the theory of nonlinear resonance circuits. 5 I

In FIG. 3 is illustrated the magnitude of the-impedance potential Uindependence upon the inductance L of the im-v pedance in a nonlineardamped oscillatory circuit, The curve 6 is also knowntromthe theory ofnonlinear-oscillatory circuits'The'p'art of the curve which is shownas asolid line indicates the stable'r'egion thereof, while that part of thecurve 6 which is shown asatlotted line is an unstable region.

From both of these diagrams of FIGS. 2 and 3 it is possible toexplainthe operation of the structure of the invention. As-

suming that the oscillatory circuit is at the stable operating point 3,shown in FIG. 2,, then it is possible, for example, by raising thepotential U, which is supplied to the oscillatory circuit, to bringabout the shifting of the linear curve 2 into the dotted line position2', so that the oscillatory circuit is brought I tronic switching stepsor the like can be controlled.

A reversal of the oscillatorycircuit in another stable location with adifferent current value can also be brought about by changing thecapacitance C or the frequency W of the applied potential U, so that achange of the slope a of the linear curve 2 can be achieved. It ispreferred however, to bringabout the reversal of the resonance circuitby way of a change of the inductance L of the oscillatory circuit, forexample, by means of a permanent magnet or by means of the current in asecondary coil on the core of an impedance which is used as theinductanceBy premagnetizing the impedance, the curve 1 can beinfluenced, and it is possible in this way to achieve a curve 1 whichwill permit the resonance circuit to have only a single stablecondition. During a change of the curve 1, into the curve I, theoscillatory circuit shifts from the stable operating point '3 into theoperating 4" where a higher current flows than at the operating point 3.

The maintenance of the impedance under the influence of the change ofthe magnetic circulation is illustrated in FIG. 3. The impedanceinitially has an inductance L, and is thus in a condition where a smallcurrent I flows, corresponding to the operating point 3 of FIG. 2. Bymeans of a. permanent magnet ii/L'which is applied'to the impedance L,the inductance of the impedance can be'reduced, for example, up to avalueL (FIG. 3). As a result the nonlinear oscillatory circuit reversesabout the point 7 of the curve 6 into the upper branchof the curve witha higher current and a higher voltage. This reversal corresponds toshifting the resonance circuit from the point 3 to the operating point 4or 4" in FIG. 2. When the premagnetizing is removed, then the originalinductance L, will again prevail, and the circuitreversed about thepoint 8 again into the conditionof lesser current. This reversal aboutthe points 7 and s can take place veryquickly.

As is apparent fromthe curve 6- of FIG. 3, a device constructedaccording to thc linvention can be adjusted in sucha waythat during alowering of the inductance of the impedance from the value L, (operatingpoint 9 in FIG. 3) to the value L (operating point 10 in FIG. 3),a-reversal of the resonance circuit about the point 7 is achieved, whileat the same time a return of the resonance circuit after removal of themagnet is retained. When the ptema gnetizingis removed, the value L, isagain achieved, but'now the circuit is at the operating point ll and areturn into the original condition about the point 8 is not possible.This situation is encountered when the inductance L of the saturatedimpedance is situated in the range between the points 7 and 8 of thecurve, through the range limited by the induction values B and 8,, forexample at a value L',. Y I

Thus, controlsconstructed in accordance with the invention and havingthe form ofanonlincar resonance circuit havean extremely wide range ofuses, a: I

FIGS. 4-7 illustrate a practical embodiment of the structure of theinvention, where the above-described reversals and shifting of anonlinear resonance circuit by means of a change in the inductance ofthe resonance circuit is used. FIG. 4

- shows in a schematic fragmentary view a commutatorless direct-currentmotor which includesa hollow-cylindrical housing at whose inner surfacea laminated, cylindrically'shaped iron body 16 is arranged, this body 16forming the magnetic return flow path for a homogeneous permanent magnetrotor 17 which is'fixed on the motor shaft 18. The armature winding 19of the motor is stationary and is, for example, fixed directly to thegrooved return flow body 16. The armature winding is, as is apparentfrom the wiring diagram of FIG. 7, divided into three equal windingsections 19a, 19b, 190, which in a manner ,similar to a three-phasewinding are uniformly distributed respect to each other by l20 at theinner surface of the stationary bearing plate 24 and are situated withinthe operating range of an arcuate magnet 25 which is fixed the motorshaft 18 for rotation therewith and thus rotates together with the rotor17. lnorder to avoid unbalance,'the magnet 25 has connected thereto acounterbalance weight 26. The three imthat at any angular position ofthe rotor one of the impedances 2022 is reliably influenced by thepermanent magnet.

As may be seen from FIG. 7, the three oscillatory series circuits, whichinclude in addition to theimpedances 20, 21, 22 also capacitors 27, 28,29 and potential takeoff coils'30, 31, 32, are connected in parallel toan oscillator 33. Atthe location of the coils 30, 31, 32 it is alsopossible to provide'ohmic resistors or capacitors. The output potentialtaken off from the coil 33 of the first'resonance oscillatory circuit,forming one of the output means, shown in FIG. 7, is delivered by way ofa diode 34 to the base of a power transistor means 35, whoseemitter/collector circuit is connected, in series with the firstarmature winding section 19a, to the direct potential driving source 36for the commutatorless direct current motor. The

, output means which is connected in parallel with the coil 31 ofresponding manner are delivered through the diodes 37 and 39 to the pairof power transistor means 38 and 40 whosev emitter/collector circuitsare respectively connected, in series with the'winding sections 19b andof the motor, to the direct potential source 36.

All three resonance circuits are situated at the operating point 3 showninFlG. 2 so that they are normally in' a condition of low current Iwhich flows through each of the resonance circuits. As soon as thepermanent magnet 25 which rotates with the rotor of the motor arrives atthe region of one of the saturated impedances 2022 of one of the threeresonance circuits, for example as shown in FIG. 7 in the region of theimpedance 22, the inductance of this impedance 22 lessens lessens itsnormal value L, shown in FIG. 3 tothe inductanceb, As a result there isa reversal of the curve 6 about the'poi'nt 7 to the operating point 10at the region of highercurrent. There thus takes place also a shiftingof the oscillatory circuit from the operating point 3 for example tolector circuit ofthe power transistor means 40 a direct current flowsfrom the potential source 36 through the winding section 19c of thedirect current motor. As soon as the permanent magnet 25, which rotateswith the rotor, moves beyond the region of the impedance 22, theoscillatory circuit returns to its initial stable operating point 3, thepower transistor 40 is blocked and the flow of direct current throughthe winding section 190 is interrupted. At this instant, however,because of the size of the permanent magnet 25, the next-followingferrite core impedance 21 of the second resonance circuit is alreadyinfluenced by the permanent magnet, and this resonance circuit shiftsinto its other operating point in the region of greater current, so thatthe power transistor means 38, by a reduction in its base potential,becomes permeable and now a flowof direct current through thewindingsection ll9b takes place.

These control and switching operations then take place at the thirdresonance circuit and from the latter will subsequently be repeated atthe first resonance circuit, so that in a continuous manner theseoperations are sequentially repeated at the successive resonancecircuits. Through the successive energizing of the three windingsections l9a-l9c, there will be provided in the direct current motor, ina known manner, a rotary magnetic field controlled by the rotor andexerting a turning moment on the rotor.

The above-described controls can be changed in different ways. Forexample, by providing a symmetrical or nonsymmetrical arrangement of aplurality of rotary permanent magnets 25, the individual windings190-190 canbe simultaneously connected to or disconnected from thesource of direct potential 36. Also, it is not essential that the powertransistors 35, 38 and 40 be actuated directly by the output potentialof the resonance circuits, and instead the plurality of power transistormeans can be provided with prestages, for example with collector-basestages (so-called emitter connections), by means of which the outputpotential of the resonance circuits are controlled.

FIGS. 8 and 9 show two additional possible changes in the circuits whichcan be considered in connection with FIG. 7. For the sake of simplicityonly one of the three resonance circuits is shown in each of FIGS. 8 and9. According to the circuit of FIG. 8, the potential taken off by theoutput means which is connected in parallel with the ohmic resistor 41,this potential being a control potential derived from the nonlinearresonance circuit which includes the impedance and the capacitor 27,undergoes a rectification directly through the emitter-base diode of thepower transistor means 35. In this way a pulsating collector current isachieved through the illustrated winding section 19a of the directcurrent motor, and if necessary this pulsating current can be smoothedby means of a capacitor 42.

With the circuit illustrated in FIG. 9, the resonance circuit I includesthe impedance 20", the capacitor 27'', and an ohmic resistor 43, andthis resonance circuit has its power delivered to a power-consumingmeans 44 (for example a winding sec tion of a commutatorless directcurrent motor) through the output means which is connected in parallelwith the resistor 43 and which includes the rectifier 45 so that thepower is derived directly from the nonlinear resonance circuit. Thus,the nonlinear resonance circuit takes over simultaneously the functionof controls and power output. Without the rectifying element 45, it ispossible to provide in the power-consuming unit 44 an alternatingcurrent. The upper limit of the power which is available to thcconsuming means 44, is determined by the maximum damping, of thenonlinear circuit, above which the circuit will no longer have a pair ofstable conditions.

The control connections can also be formed by means of linear resonancecircuits. With a small inductance control, where linear relationshipsprevail, by reason of the nonlincarity of the magnetizing curve it isalso possible to achieve with a nonsaturated impedance a change in thepotential Ur. by means of a permanent magnet, which is sufficient, forexample, to control a transistor. The sharply pronounced sudden changeswhich are achieved with a nonlinear resonance circuit, however, assure areliable operation of the device of the invention with the advantagesreferred to above.

As has already been mentioned, the use of the invention is not limitedto the above-described examples, and instead the invention relates to apractically incorporcal contact arrangement which can be used in themost widely different control installations, and, in addition, thecontrols can be brought about not only by a change in the inductance ofthe resonance circuit, but also by changing its capacitance (for exampleby using a Varactor diode), by changing the potential of the frequencyof the oscillator, and -with suitable dimensions even by way of a changein the ohmic resistancc of the resonance'circuit. Thus, the controlelements, such as the permanent magnet, can be connected to the mostwidely difiercnt types of carriers, such as for example, rotary shaftsor linearly shiftable machine components. However, they can also befixedly coupled to elements of the resonance circuit, as, for example,in the case of a control winding at the impedance or at the simultaneoususe of a Varactor diode as the capacitor of a resonance circuit. Inorder to additionally influence the output potential taken off at theresonance circuit, resistors which are dependent upon current or voltagecan be provided in the resonance circuit.

1 claim:

I. In a rotary electrical machine having a rotor and N stator windings,a high speed contactless commutator for energizing the stator windingsin sequence from a source of direct potential, which comprises:

N normally disabled gates individually connected between the statorwindings and the potential source;

N nonlinear series resonant circuits each including a saturable corereactor, a capacitor, and a noncapacitive impedance;

an oscillator;

means for connecting the oscillator in parallel with each of the seriescircuits;

means individually coupling the voltage across the noncapacitiveimpedances in the series circuits respectively to the gates for enablingeach gate when a voltage pulse appears across the associatednoncapacitive impedance;

a magnetic member coupled to the rotor for rotation therewith; and

means for mounting the N saturable-core reactors at equal angularintervals around the rotor axis adjacent and in magnetically coupledrelation to the magnetic member so that the member rotates past thereactors in sequence during each cycleot rotation of the rotor, themovement of the member past each reactor causing a gate-enabling voltagepulse to appear across the associated noncapacitive impedance of theseries circuit.

1. In a rotary electrical machine having a rotor and N stator windings,a high speed contactless commutator for energizing the stator windingsin sequence from a source of direct potential, which comprises: Nnormally disabled gates individually connected between the statorwindings and the potential source; N nonlinear series resonant circuitseach including a saturable core reactor, a capacitor, and anoncapacitive impedance; an oscillator; means for connecting theoscillator in parallel with each of the series circuits; meansindividually coupling the voltage across the noncapacitive impedances inthe series circuits respectively to the gates for enabling each gatewhen a voltage pulse appears across the associated noncapacitiveimpedance; a magnetic member coupled to the rotor for rotationtherewith; and means for mounting the N saturable-core reactors at equalangular intervals around the rotor axis adjacent and in magneticallycoupled relation to the magnetic member so that the member rotates pastthe reactors in sequence during each cycle of rotation of the rotor, themovement of the member past each reactor causing a gate-enabling voltagepulse to appear across the associated noncapacitive impedance of theseries circuit.